The luminance fall in anomaloscope examination: clinical examples

. Purpose: The evaluation of the anomaloscope slope quotient in patients with acquired colour vision deficiency. Methods: Two patients with Stargardt's disease in combination with protanomaly and deuteranomaly, respectively, were selected and also 3 patients with a presumed dominant optic atrophy of the protan type. The anomaloscope examination was performed according to the Linksz procedure. The luminance fall was calculated as the slope quotient SQ:Y units luminance fall per X units width of the matching range. Results: The SQ of the 2 Stargardt patients was steeper than the SQ of congenital colour vision defectives, especially at the red end of the anomaloscope green-red mixture scale, indicating pathologic scotopization superimposed on the congenital deficiency. In optic atrophy of the protan type the SQ was flatter than in congenital deficiency, indicating that this deficiency has nothing to do with congenital protan deficiency. Conclusion: Calculation of the slope quotient SQ is helpful for the diagnosis of acquired colour vision deficiency, especially when the subject also has a congenital colour vision deficiency or is supposed to have such a deficiency.